Melatonin and beta-endorphin changes in children sensitized to olive and grass pollen after treatment with specific immunotherapy

Background. Specific immunotherapy for respiratory allergy, a seasonal dise ase, significantly reduces the inflammatory process, attenuating the clinic al symptoms. The mechanism for the clinical beneficial effect of immunother apy has not yet been clarified. Melatonin shows a circadian and seasonal va riation and together with the endogenous opioid system plays an immunomodul atory role acting on both specific and nonspecific immunity responses. Thus , the possibility that immunotherapy involved changes in the melatonin-opio id system was investigated. Methods: Thirty-five children aged 3-15 years w ith rhinitis and asthma due to olive + grass pollen sensitization were stud ied. The patients were treated with depot extracts containing the identifie d allergens with increasing doses from 1 to 1,000 IU/ml during 3 months. Me latonin, beta -endorphin, total and specific IgE and IgG4 were determined b efore and after treatment. Results: All children showed a significant impro vement of their symptoms at the end of the treatment, coinciding with a sig nificant drop of both melatonin and beta -endorphin levels. Total IgE decre ased in most of the cases although the mean values did not show significant changes. Specific IgE and IgG4 were also unchanged. A significant correlat ion between melatonin and beta -endorphin and between beta -endorphin and I gG4 was found before immunotherapy, and these correlations disappeared when the treatment was finished. Conclusions: The decrease in the levels of mel atonin and beta -endorphin suggests the disappearance of their stimulating influence on the immune system. Thus, hyposensitization after immunotherapy may involve, at least in part, the inhibition of the immunoenhancing prope rties of the melatonin-opioid system. Copyright (C) 2001 S. Karger AG, Base l.